How to Grow Tomatoes in Containers

Nothing thrills a gardener like a generous harvest of red, ripe, rich-flavored tomatoes. While most veggies taste better home-grown, the difference between the taste of garden tomatoes and supermarket tomatoes is enough to give you vertigo. And this summer staple is possible even for those without the space for a big garden, as long as you have room on your patio or balcony for a pot or two. Below, all the info you need to know on how to grow.

Choose a Type of Tomato

Before you start, you need to pick a tomato variety. It's possible to grow any variety of tomato in a pot, from small cherries to tall beefsteak vines. But the bigger the plant, the larger a container you'll need.

Standard tomato plants can grow to 6 feet tall or more. Patio tomatoes are smaller, more compact plants, and many container gardeners swear by them, but others don't think they have the same rich taste. Cherry tomato plants are a good choice for hanging baskets.

Pick a Pot

Once you decide the tomato plants you wish to grow, you need to pick a pot to grow it in. Think big here. You want to use a container that is at least a foot square and ideally 2 feet by 2 feet. Set up the stakes or cage at the same time as you pick the pot. If you are using hanging baskets, decide where to suspend them and install secure supports so that the container doesn't fall as it grows heavy with fruit. Whatever pot you choose, be sure it has generous drainage holes in the bottom.

Select Your Soil

Tomatoes require lots of nutrients. You can pick potting soil with fertilizer mixed in, or you can add fertilizer to regular potting soil. Pick a tomato-specific, slow release fertilizer and blend it in thoroughly before you plant.

Alternatively, mix up your own potting soil. Blend three parts garden soil with three parts organic compost and two parts of builder's sand. For hanging baskets, you'll need something lighter. To make your own light soil, blend one part horticultural grade vermiculite, one part shredded peat moss and half-spoonfuls of ground dolomite limestone, superphosphate and 5-10-5 fertilizer.

Plant Seeds

All tomatoes grow from seeds, but many gardeners (especially beginners) short-circuit the process by buying seedlings, also called transplants. If you want to start seeds, sow them in moist, sterile, seed-starting mix in small pots. Dampen the sterile mix thoroughly before you put it in the pots. Sprinkle the seeds on top of the soil, several to a pot, and press them in with a pencil eraser.

Place the pots in a warm spot (like the top of a refrigerator) until the seeds sprout. Once the seedlings are a half inch tall, place the pots on a sunny, south-facing window or use artificial lights. Once the seedlings are an inch tall, thin out each pot to leave only the strongest seedling. They are ready to transplant at 2 to 3 inches tall.

Tomatoes like warmth, so wait to put the young seedlings outside until night temperatures average at least 50 degrees Fahrenheit. Even then, introduce them to the sun gradually by using a hardening off process. This means that you should put them outside in the sun only a few hours the first day, bringing them inside again at night. Keep increasing the time gradually for about a week. After that, they will be ready for transplant.

Or Buy Transplants

If you are only putting in a few tomato plants, it's easier to buy transplants from a garden store. The procedure for transplanting them into their container is the same for seedlings you raise yourself or those you buy. You'll want to sink them deep into the soil.

Many plants will die if you transplant them deeper in the soil than they were initially planted. This does not apply to tomato transplants. Young tomato seedlings grow into stronger, more productive plants if you plant them deep since they develop extra roots from the underground stem.

To accomplish this, remove the tomato seedling's lower leaves and sink the plant deep in the soil. It should be planted deep enough so that most of the stem is covered by soil. If your pot is too shallow to permit this, plant the seedling on its side in the soil to get enough of the stem covered. Deep planting encourages the plants to develop more and stronger roots.

Secure a Sunny Spot

Tomatoes love sun, and, what's more, they must have direct sun to grow. It's easy to underestimate the plants' sun requirements or overestimate the amount of sun your patio gets. But the key to success with container tomatoes is between 6 and 8 hours a day of full sun. Don't try to cheat Mother Nature on this one! If you need to, use a sunlight meter and keep checking as the growing season slips by since the amount of sunlight that hits a particular patio corner can change significantly.

Water Appropriately

The key to irrigating your young container tomatoes is to keep the soil moist but not wet. The amount of water your plant needs depends on many factors, including temperature, wind, humidity, and pot size. A small plant in a mild region may get by with a few waterings a week, while a big plant may need daily watering in a hot region in mid-season.

To determine if your plant needs water, dig a finger down into the soil to an inch below the surface. If the soil there is dry, water the plant thoroughly. Don't stop until water runs out of the drainage holes. If the soil an inch deep is moist, don't water, but check again the following day.

When you water your plants, remember to put the water on the soil, not on the foliage. Water on foliage can cause diseases like blight and fungus.

From Alaska to California, from France's Basque Country to Mexico's Pacific Coast, Teo Spengler has dug the soil, planted seeds and helped trees, flowers and veggies thrive. A professional writer and consummate gardener, Spengler has written about home and garden for Gardening Know How, San Francisco Chronicle, Gardening Guide and Go Banking Rates. She earned a BA from U.C. Santa Cruz, a law degree from U.C. Berkeley's Boalt Hall, and an MA and MFA from San Francisco State. She currently divides her life between San Francisco and southwestern France.